Ballistic helmet body

ABSTRACT

A ballistic helmet body made up of a plurality of plies formed from flat hexagonal blanks of ballistic fabric. Before being formed to the shape of the helmet body each blank is slit along lines extending from spaced points around the periphery thereof toward the center to form a generally circular central area and a plurality of contiguous segments extending outwardly from the central area. When the blanks are formed to the shape of the helmet body, adjacent segments overlap over first portions to leave second portions which do not overlap. As successive plies are laid up they are relatively oriented so that second portions of one ply are covered by first portions of another ply.

This is a divisional of co-pending application Ser. No. 06/925,083 filedon Oct. 30, 1987, now U.S. Pat. No. 4,778,368.

FIELD OF THE INVENTION

The invention is in the field of ballistic helmets and more particularlyrelates to an improved method of making helmets which makes mostefficient use of the base ballistic material.

BACKGROUND OF THE INVENTION

Ballistic helmets are well known in the prior art for use by persons toprotect them against serious injury from shrapnel and other missiles.Most modern ballistic helmets are made from a plurality of plies ofballistic material which are laid up in a mold and shaped to theconfiguration of the helmet.

A material which is eminently suited for use in making ballistic helmetsis one which is made from one of the "aramids" which include aromaticpolymide resins developed by E.I. duPont de Nemours and Company and soldunder the trademarks "Kevlar" and Nomex". This material is relativelyexpensive. In addition, a considerable quantity of material is used inmaking up a helmet shell owing to the fact that a relatively largenumber of plies are required to produce a helmet affording the desireddegree of protection. It will be apparent that the most efficient use ofthe available materials in making up the individual plies is highlydesirable.

Generally speaking, two methods are known in the prior art for formingblanks from which the individual plies of the helmet body can be made.In the first of these methods which is exemplified by the disclosure ofDaly U.S. Pat. No. 2,532,442, individual unitary blanks are custom cutfrom the ballistic material prior to being laid up in the forming mold.While this method results in a high quality method having good ballisticproperties, it does not make efficient use of the basic material, muchof which is wasted in the custom cutting process. In the second methodwhich is exemplified by Grick U.S. Pat. No. 4,596,056, a plurality ofindividual pieces are joined together by any suitable means to form theblank which is laid up into the mold. While this method permits a moreefficient use of the available base material it is relativelycomplicated and time consuming. In addition, under certain circumstancesthe pieced up plies have not met customer specifications.

SUMMARY OF THE INVENTION

One object of my invention is to provide an improved method of makingballistic helmets.

Another object of my invention is to provide a ballistic helmet made bymy improved method.

Still another object of my invention is to provide a method of making aballistic helmet which makes most efficient use of the base material.

A still further object of my invention is to provide an improved methodof making ballistic helmets which is rapid and expeditious.

Yet another object of my invention is to provide an improved method ofmaking a ballistic helmet which makes efficient use of the base materialwhile at the same time satisfying all of the customer's specifications.

A still further object of my invention is to provide an improved methodof making ballistic helmets without sacrificing any degree of protectionafforded by the helmet.

Other and further objects of my invention will appear from the followingdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings to which reference is made in the instantspecification and which are to be read in conjunction therewith and inwhich like reference characters are employed to indicate like parts inthe various views:

FIG. 1 is a schematic view of a mold used in my improved method ofmaking ballistic helmets.

FIG. 2 is a fragmentary view of a sheet of the base ballistic materialillustrating the manner in which I cut the ply blanks.

FIG. 3 is a plan view of one form of ply blank which I may employ in myimproved method of making ballistic helmets.

FIG. 4 is a plan view of an alternate form of ply blank which I mayemploy in my improved method of making ballistic helmets.

FIG. 5 is an elevation of a configuration of a blank after it has beenformed in the mold of FIG. 1 in the practice of my improved method ofmaking ballistic helmets.

FIG. 6 is an elevation of the blank of FIG. 5 rotated throughapproximately 60° about the vertical axis thereof.

FIG. 7 is a fragmentary partially schematic view illustrating the laidup assembly of plies of one form of ballistic helmet made by my improvedmethod of forming ballistic helmets.

FIG. 8 is a schematic view illustrating one of the features of myimproved ballistic helmet.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawing, as will be apparent from the descriptionhereinbelow, in making a ballistic helmet body pursuant to my improvedmethod, I lay up a plurality of superposed plies 14 in the cavity of afirst die 10. When a predetermined number of plies have been laid up,the complementary die member 12 is moved under pressure into the cavityof the die 10 to form the plies to the shape of the helmet body. Thisoperation of moving the dies 10 and 12 into cooperative relationship maybe carried out one or more times in the course of formation of acomplete helmet body.

In practice of my method of making ballistic helmets, I make optimum useof the base ballistic fabric. For example, with an available sheet,indicated generally by the reference character 16, of a fabric made froma suitable material, such for example as "Kevlar", I cut the individualblanks 18 from the sheet. I have discovered that a hexagonal shape ofblank, both is a very nearly ideal shape for forming a helmet ply andalso permits of the most efficient use of the material of the sheet 16.

It will be noted that in the course of cutting the sheet to form theblanks 18 along one edge thereof, I leave remnant pieces 20 which are inthe form of a hemihexagon. Along the other edge of the sheet 16 I leaveremnant pieces 22 and 24.

In adapting a blank 18 to serve as a ply of a ballistic helmet, I cutthe blank 18 along lines 26, 28, 30, 32, 34 and 36 extending from theapices of the hexagon inwardly toward the center thereof. Each of thecuts extends for a distance D from an apex toward the center of theblank to result in a generally circular center portion 38 having adiameter B and segments 40, 42, 44, 46, 48 and 50 extending outwardlyfrom the center portion 38. I select the dimensions A, which is thedistance between a pair parallel sides of the hexagon, and C, which isthe length of one of the hexagon sides, in accordance with the size ofthe ply at that particular location in the helmet body.

In the practice of my method, I am also able to make full use of theremnant pieces 20 and some use of the remnants 22 and 24. As can be seenby reference to FIG. 4, a pair of remnants, 20a and 20b, may be placedwith their longest sides in abutting relationship along edges 52a and52b to form a full hexagon. With the parts in this position, a piece 54of ballistic material cut from one of the remnants 22 and 24, forexample, is secured to the two remnants 20a and 20b by any suitablemeans, such for example by ultrasonic welding. It will readily beappreciated that the piece 54 has a length which is substantially equalto the diameter B and is placed on the two remnants, 20a and 20b, sothat it extends over the full length of the diameter B before beingwelded in place. When it has been welded in place, the resulting blankhas the same general configuration as does the blank shown in FIG. 3.

While a helmet shell made entirely of the blanks of the type shown inFIG. 4 might not be acceptable to certain user, the helmet incorporatinga minimum number of such blanks would be acceptable.

Referring now to FIGS. 5 and 6, I have shown the configuration of ablank after having been laid up in the mold member 10. In this conditionof a blank, it will readily be seen that adjacent segments 40, 42, 44,46 and 48 overlap each other with, for example, the segment 44overlapping the segment 46, the segment 46 overlapping segment 48, andso forth. The amount of overlap is such that each blank or ply in thiscondition includes first portions which are overlapped so as to be ofdouble thickness and second portions which are not overlapped so as tobe of only single thickness. Owing to that fact, I rotate successiveblanks or plies as they are laid up in the mold so as to ensure that thesecond unlapped portions of one ply are covered by first or overlappedportions of other plies. More specifically, I rotate each successivelayer through such a distance that the fourth layer registers with thefirst.

Before laying up the various plies in the mold, I calculate the sizes ofthe various plies at various locations necessary to give the requiredthickness of ballistic material at that location in the finished helmet.In performing this calculation a series of circles were struck atdifferent distances from a vertical center line on the top of the crownof a finished helmet having the desired configuration. Next, acalculation was made as to what the needs would be in perimeter inchesat that particular area of the helmet to give the desired materialthickness.

It will readily be appreciated that the number of plies, the dimensionsof the various plies and the manner of laying the plies up varies withthe type and size of the helmet. By way of example, in the table below Ihave outlined the dimensions of nineteen plies which required to make upone configuration of helmet or helmet preform.

    ______________________________________                                                 (INCHES)                                                             PLY NO.      A     B          C     D                                         ______________________________________                                         1           20    6          11.548                                                                              8.548                                      2           20    6          11.548                                                                              8.548                                      3           20    6          11.548                                                                              8.548                                      4           16    6          9.237 6.237                                      5           20    6          11.548                                                                              8.548                                      6           12    6          6.928 3.928                                      7           20    6          11.548                                                                              8.548                                      8            8    6          4.619 1.619                                     *9           20    6          11.548                                                                              8.548                                     10            8    6          4.619 1.619                                     *11          20    6          11.548                                                                              8.548                                     12            8    6          4.619 1.619                                     13           20    6          11.548                                                                              8.548                                     14            6    6          3.464 0.464                                     15           20    6          11.548                                                                              8.548                                     16            6    6          3.464 0.464                                     17           20    6          11.548                                                                              8.548                                     18            6    6          3.464 0.464                                     19           20    6          11.548                                                                              8.548                                     ______________________________________                                         *May be according to FIG. 4.                                             

From the discussion thus far, it will readily be apparent that myimproved method is especially adapted for use where kits containing theblanks necessary to make up a particular model and size of helmet aresupplied to the user. For example, where a helmet preform of the typeadapted to be made up with the blanks of Table 1 is to be made, theoperator is supplied with a kit containing those blanks in the correctnumber and sequence. Multiple kits are stacked with a separator of anysuitable type between each kit.

In practice of my improved method of making a ballistic helmet preform,each of the plies is formed in the manner described hereinabove fromballistic cloth which preferably is an aramid resin readily availablefrom a number of suppliers under different trade names. In practicing mymethod, the material of which the plies are made is coated on both sideswith equal amounts of laminating resin which may, for example, be acatalyzed system composed of 50% phenol formaldehyde and 50% polyvinylbutyral resins.

By way of example, in the formation of a preform according to Table Iwith molding apparatus illustrated in FIG. 1, to produce the lay-upillustrated in FIG. 7, the operator first folds the first blank or outerdisc pinwheel generally to the configuration of FIGS. 5 and 6, takingcare that all flaps or overlapping portions of the folds run in the samedirection. The folded blank is then placed in the mold member 10. Next,the blank which is to form ply 2 is folded, making sure that all theflaps run in the same direction and this folded blank is placed in themold member 10 over the first blank with the second and succeeding pliesbeing rotated a sufficient amount relative to the first so that everyfourth blank registers. This is illustrated in FIG. 8 in which each of aplurality of adjacent plies P1 through P4 is shown to have a referencepoint R with the rotation of the plies being such that the point R of P1registers with the point R of P4. The next six plies up to ply 8 arepositioned in the mold and the mold member 12 is moved into the cavityof the mold member 10. After the next four plies are placed in the moldcavity in the manner described, the press is again operated. The nextfour plies are inserted in place and the press is operated. Then thelast three plies are positioned and the mold plug 12 is moved into thecavity of the member 10. When that has been done the completed preformis sealed around the edges thereof with a heat gun. The completedpreform may then be removed from the mold member 10.

It will be seen that I have accomplished the objects of my invention. Ihave provided an improved method of making ballistic helmets and aballistic method made thereby. My method makes most efficient use of thebase material of which the helmet is formed. My method is rapid andexpeditious. My method makes efficient use of the base material while atthe same time satisfying all of the user's specifications. My methodmakes most efficient use of the base material without sacrificing anydegree of protection to the wearer.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of myclaims. It is further obvious that various changes may be made indetails within the scope of my claims without departing from the spiritof my invention. It is, therefore, to be understood that my invention isnot to be limited to the specific details shown and described.

Having thus described my invention, what I claim is:
 1. A ballistichelmet body including in combination a plurality of plies of ballisticmaterial, each of said plies being formed from a flat hexagonal blank ofballistic fabric having slits extending from spaced locations around theperiphery thereof toward the center to form a central generally circulararea and a plurality of contiguous segments extending from said centralarea, the edges of adjacent segments of said blanks abutting along saidslits, adjacent segments of each of said plies overlapping to provideeach ply with first portions which overlap and with second portionswhich do not overlap, successive plies being oriented relative to eachother so that second portions of one ply are covered by first portionsof another ply, said plurality of plies including a number of plieswhich decrease in size from the outer surface toward the inside of saidbody.
 2. A ballistic helmet body including in combination a plurality ofplies of ballistic material, each of said plies being formed from a flathexagonal blank of ballistic fabric having slits extending from spacedlocations around the periphery thereof toward the center to form acentral generally circular area and a plurality of contiguous segmentsextending from said central area, the edges of adjacent segments of saidblanks abutting along said slits, adjacent segments of each of saidplies overlapping to provide each ply with first portions which overlapand with second portions which do not overlap, successive plies beingoriented relative to each other so that second portions of one ply arecovered by first portions of another ply, said plurality of pliesincluding a number of first relatively large plies and a number ofsecond relatively small plies, each of said second plies beingsandwiched between a pair of first plies, said number of second pliesincluding plies which decrease in size from the outside to the inside ofsaid body.
 3. A ballistic helmet as in claim 2 in which the portions ofone ply are staggered with relation to the portions of an adjacent ply.